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"To the dull mind all nature is leaden. To the illumined mind the whole world burns and sparkles with light." -- Ralph Waldo Emerson

States of Matter:

SOLIDS, LIQUIDS, AND GASES

MATTER  AND  TEMPERATURE

Concept Pages:

Physical Science "Key Concepts" Home Page


Section Review questions
Chapter review questions
4 States  of  Matter:
- Solid
- Liquid
- Gas
- Plasma
Depends on temperature
Characteristics   Of  The  States  of   Matter
SOLIDS
• Definite shape

• Definite volume (not taking high pressure into account)
WHY?
Kinetic Theory of Matter
-Tiny particles (atoms and molecules) that are in constant motion make up all matter.

-Particles that make a solid held together by forces between the particles.
They stay together if there isn't enough energy to break that bond.
Crystalline solids
In most solids -
• The particles that make up the solid are arranged in repeating geometric patterns called crystals.

• Different substances have different crystal shapes.
Noncrystalline solids
• Glass, many plastics, some kinds of wax are solid but are not made of crystals.

       - Called amorphous solids, meaning "having no form."

      - Sometimes classed as thick liquids.
LIQUIDS
• Flow

• Take shape of container, up to their volume.

• Definite volume (not taking high pressure into account)

More Motion:
Kinetic Theory of Matter also explains liquids.

It states that -
 The particles of a liquid are more energetic than solids.
-Though they can't be squeezed into a smaller volume normally.

-They can move around each other, unlike solids, changing shape according to their location or container.

-Because their bonds are a little looser than in a solid.
GASES
• Expand or contract to fill the volume available.

• Take shape of container.

 
Kinetic Theory of Matter
States That:  The particles of a gas have enough energy to totally break the bonds holding them together.
PLASMA
Kinetic Theory of Matter also explains the very energetic state of plasma.
  • The temperature is so high that the forces holding the parts of the atoms together are broken.

      -The bonds break and atoms break apart into their constituent parts.

      - Protons, Neutrons, and Electrons

        +  Protons are positively charged
        --  Electrons are negatively charged
So Plasma is:
  • A mixture of positively and negatively charged particles.
  • Temperatures can be considered relative
  • It takes a lot less heat to break the bonds holding water molecules together in ice than it does rock, or steel, for example.
 

THERMAL EXPANSION

Kinetic Theory of Matter explains changes within a state:
  • Most matter expands as it gets hotter

      - It takes up more space

    Examples include:

 
  • Expansion joints in bridges
  • Thermometers

Changes In the State of Matter

Name of Action or Change of State

Action or Change of State

 Example
Freezing  Liquid to solid Placing an ice tray in the freezer turns the water to ice
Melting  Solid to Liquid Put an ice cube into your drink and it goes away
Boiling/Evaporation  Liquid to Gas Boiled water steams or a puddle on the sidewalk evaporates
Sublimation  Solid to Gas Moth balls disappear after a time
Sublimation  Gas to Solid Frost appears on your car windshield
Condensation  Gas to liquid Clouds in the sky or your bathroom mirror after a hot shower
 

Kinetic Theory of Matter also explains changes of state:

 
Add Energy to move: 
from solid:
to liquid:
to gas:
to plasma.
   
Take Away Energy to move:       from plasma:
      to gas:  
    to liquid:    
  to solid.      
Heat  of Fusion
Is the energy needed to change a solid to a liquid.
Heat  of Vaporization
Is the energy needed to change a liquid to a gas.
  • So, it is the energy that causes evaporation.

BEHAVIOR OF GASES

Pressure
The amount of force exerted per unit of area.
  • Gases exert pressure by colliding with things -

• Other particles of gas

• Sides of the container

• Objects within the area of the gas, like you.

           

 Formula For Figuring Out Pressure: P = F/A

 

The Pascal (Pa) is the SI unit of pressure:

 
1 Pascal = 1N/m2
The kilopascal (kPa) is more commonly used because the Pa is a very small amount of pressure.

• At sea level, at STP (standard temperature and pressure):

1atm is 101.3 kPa  (101,300 Pa),
      or
            101,300 N/m2

         

Our  Atmosphere
We live within the lowest layer called the troposphere:

- As altitude increases, pressure drops.

• At 5 km above sea level, air pressure is ~ 54 kPa

• At 50 km, it is ~ 0.15 kPa

 
Boyle's  Law
•  At constant temperature:

Decreased volume = Increased pressure

    also

Increased volume = Decreased pressure

         
Charles's  Law
•  At constant pressure:

Increased temperature = Increased volume

    also

Decreased temp = Decreased volume

         
The  Kinetic  Theory  of   Matter, applied to Charles's Law, would state that:
If you caused all motion within the atom to cease,
the temperature would be

            Absolute Zero,

          0 K, or -2730C

          - A complete absence of heat OR motion!!

           

PRINCIPLES   OF FLUID  BEHAVIOR

Buoyant  Force
The ability of a liquid or gas - a fluid - to exert force upward (opposite the force of gravity) on an object within that fluid
To float.......................Buoyant force = Weight of object
To sink.......................Buoyant force < Weight of object
To move upward........Buoyant force > Weight of object

Archimedes's  Principle
The buoyant force on an object in a fluid is equal to the weight of the fluid displaced by that object.

 
A Little Story:

     Archimedes was commissioned by the King to determine whether a fine gold gift, a crown, was pure gold without marring it in any way.  He supposedly thought of this principle when, while bathing, he got into the tub (or pool, or spa, or whatever they bathed in back in ancient Alexandria) and then ran through the streets (sans clothing) shouting "Eureka," (I've found it!).  He was quite possibly most pleased at the prospect of continued life, since a lot of Kings back then were homicidally intolerant of failure.

 

How this works, very basically:

The wreath and the gold nugget have equal weight.  Place in water and...

 

    The wreath displaces more water than the gold nugget.

What does the above illustrate?  Why does the wreath appear to weigh less when the two are placed in the water?

    (These illustrations are from Drexel University Archimedes page.)

     
Pascal's Principle
 
 Pressure applied to a fluid is transmitted unchanged throughout the fluid.

•  Hydraulic systems are a major application of this principle.

           

          Remember: P = F/A
So
- if A is the area of the cross section of a cylinder,
 

    - and you have 2 different size cylinders, with pistons,

      - and you apply 500N of Force to the piston of the smaller cylinder with an
        area of 5cm2
- expressed in the formula like this:
P = 500N = 100N
        5cm2    1cm2
 

        then the pressure of 100 N/cm2 will be transferred throughout the fluid equally,

      •   including to the larger cylinder's piston,
          - with an area of 50cm2
              - at a Pressure of 100 N/cm2 x 50cm2 = 5,000 N/cm2
Click for illustration
So, it is possible for a mechanic to lift a 6,000 pound truckwith only a few pounds of pressure on the end of the handle of a hydraulic jack.

 
Bernoulli's Principle
As the velocity of a fluid increases, the pressure exerted by that fluid decreases.

    •  A plane's wing is curved so that the air going the greater distance over the top of the wing moves faster,

        - Reducing pressure from above,

        - Allowing the lift from below to raise the plane up:

The bluest areas are the lowest pressure, the redder are the highest.
(This illustration from John S. Denker, where you will find a different viewpoint about how planes can fly.  Very good reading, go there!)

Updated 10/14/07